Call 911 in the event of a medical emergency. It's what we have been taught and it's what we teach our kids. But producer Liz Wagner, reporter Vicky Nguyen and photographer Felipe Escamilla uncovered that at the United States Postal Service, the rules governing what to do in an emergency are very different. And those rules may have caused critical delays in life and death situations. Through interviews with sources, internal postal service documents and public records, the NBC Bay Area Investigative Unit exposed that USPS policy instructs employees to call their supervisors and then security in the event of a medical emergency—not 911.